A multicenter cooperative group of neonatal intensive care units is to be organized for concerted efforts to scientifically evaluate treatment regimens applied to sick newborns. The network of individual NICU's is organized to pursue common protocols in the study of their respective patients so that evaluation of the aggregate population will yield results rapidly and perhaps definitively. Phases 1 through 4 are planned to identify issues for study, to evolve study designs for common application in participating institutions, to gather data according to established protocols, to decide when to terminate studies in progress and analyze collected data, and to resume the cycle with plans for new endeavors.